I am not a computer person. Firefox updated itself today. My opening page is Google. I have had a beautiful artwork background photo on the opening page for several years now. Today it disappeared after the Firefox update. How do I get it back?

I am not a computer person. Firefox updated itself today. My opening page is Google. I have had a beautiful artwork background photo on the opening page for several years now. Today it disappeared after the Firefox update. How do I get it back?